Just picked up a 460 (and truck) from a guy that said it had been rebuilt with 1500 on it. I confirmed with the machine shop that they rebuilt the block as he said. Someone had 'stolen' the radiator between him telling me about it and me going to see it so we only started it for about 5 seconds.
I get it home, hook up a radiator and start to perform a flush (water hose on low in the lower radiator hose). Never even get to the motor running part of the process. I notice water pooling at the distributor. I turn off the water, blue towel it out, and turn the water on even lower to watch the leak. Looks like it's all coming from the intake manifold gasket.
Stop the test and decide to drain the oil. The oil looked ok, seemed a little thin but didn't look milky.
So besides replacing the intake gasket, is there anything else I should check while I have the intake off?

 

It is worth checking the intake and heads for cracks in the water jackets. Hook up the hoses and do a real pressure test when you put it back together.

 

Thanks.
Suggestions for best intake manifold gasket? Seems like there are a few out there.

 

I've never tried any other gaskets besides the fel-pro kits from napa, because they have done well for me. The trick is to have all old gasket material and debris cleaned off of the mating surfaces. The best gasket will not seal a poorly prepped surface.